1. Field of the Invention
The present invention relates to therapeutic devices. More specifically, the present invention relates to methods and systems for helping patients improve mastication and deglutition. The present invention also has application to the movement of an object on a visual display in order to activate an electrical apparatus, and to methods for facilitating typing on a digital keyboard.
2. Technology in the Field of the Invention
Mastication, or chewing, is the process by which food is mashed and crushed by teeth. Mastication increases the surface area of food and allows it to more efficiently be broken down by enzymes. This is the first step of digestion.
During the mastication process, food is positioned between the teeth for grinding by the cheek and tongue. As chewing continues, the food is made softer and warmer. Enzymes in the saliva begin to break down carbohydrates in the food. After chewing, the food (now called “bolus”) is swallowed. It enters the esophagus and continues on to the stomach where the next step of digestion occurs.
Many foods require at least some chewing for proper digestion. However, some individuals lack the muscular ability to grind food with their tongue and teeth. Physical difficulty in chewing food may arise in young patients due to a neurological or muscular birth defect. Alternatively, such a difficulty may arise in older patients due to a partial stroke or injury. Such individuals are thus limited in what they can eat.
There are also some individuals who have trouble swallowing food and saliva. All food and saliva must be swallowed. Patients who lack the muscular ability to swallow cannot eat properly. Such a condition is referred to as dysphagia.
Swallowing, or deglutition, is the complex process by which food and saliva are moved from the mouth, through the pharynx, and into the stomach. Both food and air pass through the pharynx, a part of the neck and throat positioned immediately posterior to the mouth and the nasal cavity, superior to the larynx, esophagus, and trachea. In other words, the pharynx (along with the esophagus and larynx), is part of both the respiratory system and digestive system in humans.
Deglutition is actually a two phase process involving both the somatic (voluntary) and autonomic (involuntary) nervous systems. For swallowing, the voluntary phase is referred to as the buccal phase, while the involuntary phase occurs as food is moved from the oral cavity into the pharynx.
Concerning the buccal phase, this phase occurs when a bolus, a soft mass of sufficiently chewed food mixed with saliva, is transferred to the back of the tongue. The anterior portion of the tongue lifts toward the hard palate in the mouth and then descends backwards to force the bolus into the pharynx. Next, the posterior portion of the tongue lifts toward the soft palate, elevating the uvula to seal off the nasopharynx. This prevents the bolus from entering the nasal cavity. The buccal phase involves cranial nerves V, VII, and XII, and is controlled by the somatic nervous system.
Once the bolus has entered the pharynx, receptors trigger an involuntary response by the deglutition center in the brain. This pharyngeal-esophageal phase involves cranial nerves V, IX, X, XI, and XII. Pharyngeal folds on either side of the bolus are drawn together to create a narrow passageway. The bolus is forced through the pharynx by peristalsis, which is a series of involuntary muscle contractions. At the same time, the hyoid bone and larynx move upward and forward. This causes the epiglottis to swing backwards, where it blocks the opening to the larynx. The bolus can now pass only into the esophagus; all other openings have been blocked. The esophageal sphincter relaxes, allowing the bolus to enter.
During the brief time that the larynx is sealed off, the swallowing center directly inhibits the respiratory center, halting respiration. Once the bolus enters the esophagus, peristalsis continues to force the food onward toward the stomach while the pharynx returns to its resting state. This is the involuntary process which occurs once food enters the pharynx.
During respiration, air travels from the oral or nasal cavity into the pharynx and then on through the larynx to the trachea and lungs. When food is swallowed, it travels from the oral cavity into the pharynx, and then into the esophagus. During swallowing, a flap of tissue called the epiglottis (part of the larynx) folds down to direct food away from the trachea and into the esophagus, thus preventing aspiration of food into the lungs. Faulty chewing or swallowing may lead to malnutrition, dehydration, airway obstruction (choking), aspiration pneumonia, and even death.
Dysphagia may arise in young patients due to a neurological or muscular birth defect. Alternatively, it may arise in older patients due to a partial stroke or loss of muscle strength. If the muscles of the tongue or cheek are weak or are not functioning properly, it may be difficult to move food around in the mouth for proper chewing. Food pieces that are not chewed properly may be too large to swallow and can block the passage of air when they enter the throat.
A need exists for a device that assists patients in strengthening the intra-oral musculature and in improving muscular control in connection with mastication and deglutition. A need further exists for a system by which a patient's ability to chew and swallow food may be improved by means of muscle therapy and visual feedback. A need further exists for an intra-oral system by which an individual may control an object on a visual display for activating an electrical apparatus. Finally, a need exists for a system that enables the typing of characters on a virtual or digital keyboard.